A candidate active antenna design for a low frequency radio telescope array

Abstract

The Long Wavelength Array (LWA), currently in the development stage, is a radio telescope array that will be constructed in New Mexico, USA over the next several years. It will consist of ~ 52 stations of ~ 256 cross-dipole antennas each, and will explore the Universe in the 20 - 80 MHz frequency band. The large number of antennas required for the LWA suggests that the antenna design must be kept simple in order to maintain a low station cost. The leading candidate LWA antenna is a "big blade" antenna consisting of crossed dipole elements made of sheet aluminum. The big blade antenna has been extensively characterized and shows potential for fulfilling the technical requirements for the LWA. However, their potentially prohibitive cost has necessitated the exploration of alternate, more affordable antenna topologies. In this paper, we present one such promising topology - the fork antenna. In the following sections, we show through simulation and field measurement that the fork antenna compares closely in performance to the big blade antenna and is therefore a viable alternative to the big blade antenna in the LWA project.